The invention relates to correlators and more specifically to correlators which include and comprise processing capability of received signals through the use of Random Access Memory (RAM) means.
Spread spectrum communications involve using more bandwidth than is theoretically needed to transmit digital data. Motivation for using spread spectrum signals is generally based on interference suppression, energy density reduction and/or time delay measurement. Direct sequence, pseudonoise, frequency hopping, time hopping and linear frequency modulation are generic types of spread spectrum signals which may be used alone or in combination with each other dependent upon user requirements and system capacity.
A matched filter, typically a correlator, provides at its output the maximum possible peak-signal power/average-noise power ratio when the input is a known signal and a random noise component. Matched filters are implemented in a variety of elements and may be periodic, non-periodic, autocorrelated or cross correlated. Traditional implementations require dedicated circuitry for each correlator and associated devices in a multi-frequency application. Alternatively, some single frequency implementations have utilized memory devices in a limited fashion to provide code correlation.
There currently exists a need for implementing correlator functions using minimum circuitry and elements that have maximum application flexibility.